This observational study will investigate the developmental immunology of peanut, egg, and milk allergy in a cohort of milk- or egg-allergic children who are at risk for peanut allergy. This strategy will help to delineate, compare, and contrast biological markers and immunologic changes associated with the development of peanut allergy and loss of egg and milk allergy, while simultaneously evaluating important clinical and environmental influences likely to account for the recent rise in the prevalence of these allergies. The hallmark of food-allergic disease is the production of food-specific IgE antibodies that represent an end result of a Th2 influenced immune response. Currently, there is only a limited understanding of the mechanisms involved in the developmental course of food allergies. To effectively prevent or reverse the progression of food allergy, immune interventions will be needed. Furthermore, it is likely that successful strategies will need to be directed to those persons at identifiable risk (e.g., who have biomarkers associated with development of peanut allergy).

This study duration is planned for 5 years. There will be at least 7 study visits; at each study visit, medical, allergy, and diet history will be noted. At study entry, stool samples will be collected from infants and dust samples will be taken from their homes to assess for endotoxin and allergens in the home environment. At selected visits, participants will undergo a physical exam, atopic dermatitis and asthma evaluations, and blood collection. Oral food challenges will also occur at some visits, as clinically indicated. Infants will receive standard of care advice for treatment of egg, milk, and peanut allergy for the duration of the study.

In addition to the infants enrolled in this study, their full siblings will be asked to join the study as either genetic or mechanistic study controls, or both; controls will undergo allergy history at study entry. Siblings participating in genetic testing will have DNA collected by cheek swab; siblings participating in the mechanistic studies will have blood collected.